System of recording vibrations and reproducing same



Sept. 2, 1930. s. N. BARUCH 1,774,821

SYSTEM OF RECORDING VIBRATfONS AND REPRODUCING SAME Filed Feb. 4, 1929 INVENTOR SYDNEY N BARl/CH ATTORNEY Patented Sept. 2, 1930 UNITED STATES SYDNEY N. .BARUCH, OF NEW YORK, N. Y.

SYSTEM OF RECORDING VIBRATIONS AND REPRODUCING sm 7 Application filed February 4, 1929. Serial No. sense.

The invention relates to the recording of signals, sound, etc., as represented by electromagnetic impulses, as well as to the reproduction thereof; and more especially by means of a telegraphone which, as is wel known, comprises a moving magnetizable Wire or surface which is locally magnetized in varying degrees at successive points along the same, whereby when the said wire or the like thus magnetized is placed in proximity to a suitable coil, the variously magnetized spots thereof will reproduce in said coil fluctuations of current. In the production of records on such magnetizable wire or surface. it has been found that there is distortion in the reproduced signal as a result of some previous history in the wire, more especially in connection with the manufacture of said wire and due to a set of its molecules.

The invention contemplates the novel method for eliminating the effects of such set and the production of a new reproducing element of the type which is magnetically saturated except for the portions representing the recorded matter. This is accomplished by first bringing the wire or magnetizable surface to a state Where it is magnetically saturated or magnetized to the limits of the hysteresis curve, i. e., polarized beyond the knee of the same, and thereby wip ing out all previous history and permanently setting the molecules. The wire is then subjected, without further polarization, to a fluctuating magnetic field produced by the signalling current which it is desired to record and which is of an alternating nature, it.

being understood, of course,thatthe positive half of thesignal will not be recorded while the negative half cuts into or reduces the degree of saturatiomor vice versa, to produce thereby spots along the wire correspond- .ing to the impressed signals. Naturally, the

output signal current will be somewhat decreased thereby, but this is compensated for by the greater fidelity in reproduction resultmg.

I am aware that it has been proposed, as in U. S. Patent No. 1,459,202, to eliminate all previous history from magnetizable bodies of this nature either by first subjecting the wire to an oscillating current of high frequency or by first magnetizing the samesubstantially to the saturation point and then when impressing thereon the signal current with a component of magnetism of polarity opposite to that to which the wire was initially subjected. In neither case, therefore, will the wire be left in part in a saturated state with the signal portions cut out there-. from. a

The invention has for its object, also, an improved form of magnetizing and reproducing coil for the magnetizable body and record, as well as novel means for the reproduction of the said record whereby the somewhat lesser strength signals'may be-reproduced with ample volume. I To this end, provision is made for concentrating the magnetic flux to be applied to the magnetizable body as nearly as possible inits linear direction. For example, the coil of magnetizing windings may be formed as a bobbin with central opening through which the magnetizable body is to be drawn, the said windings being enclosed between two interfitting cups or 'shells of metal centrally perforated to register with the opening of the bobbin and each having a tooth projecting radially inward and the two teeth, thus displaced in the line of travel of the magnetizable body, serving as the poles of the magnet. The nature of the invention, however, will best be understood when described in connection with the accompanying drawings, in which:

Fig. 1 is-a diagrammatic representation of the connectionsand apparatus suitable for carrying out the method of my invention.

Figs. 2 and 2 are representations of hysteresis loops for use in the explanation of my invention. Fig. 3 is a fragmentary view of a section of wire, on an enlarged scale, affording a graphic representation for purpose of explanation of the magnetic conditions revailing in the wire when a record has een impressed thereon. Fig. 4 is a part vertical section and elevation of a coil which may be utilized for magnetizing, or as a pick-up device; and Fig. 5 is a fragmenta end elevation thereof.

Fig. 6 is an e evation of a modified form of magnetizing or pick-up device.

Referring to the drawm more particularly Figs. 1, 2, 2 and 3 t ereof, the novel method involves magnetically saturating a magnetizable member, for example the wire 20, as by drawing the same through a magnetizing device 21 which may be of the nature hereinafter more fully described, a field therefore being produced by the storage battery potentiometer 22 when the circuit is closed at the switch 23. The intensity of field produced thereby'is so selected that the wire 1s magnetized to a degree of saturation, or super-saturation, that is to say, beyond the point 24. or knee of the hysteresis loop, Fig. 2. To this end, the material'selected is of 1 particularly high retentivity so that the knee portion of the curve becomes somewhat flatter, as indicated in Fig. 2.

The'wire, having thus been provided with a permanent magentic set, is drawn through a similar electromagnetic device 25 included in the secondary circuit of a transformer 26 whose primary is included in the signal circuit and having, for example, the microphone 27 as a modulating element. The electromagnetic fluctuations produced there by will act on the wirepassing through the device 25 to reduce proportionately its magnetization, the positive half of the signal wave not being recorded at all, while the negative half effects the reduction of magneti'zation, or vice versa. Spots are thereby produced along the wire which correspond to the impressed signals, an attempt being made to represent thesame at the half wave portions 28 of the wire section 20, Fig. 3, the

initial magnetization of wire being indicated by the'stippled portion.

I have found that by concentrating the magnetic flux in the production of the aforesaid records in as near a linear direction as possible on the wire, that a much clearer reproduction is attainable; and to this end, it is preferred to utilize a magnetizing device of the nature shown in Figs. 4-6, inclusive. in these devices, a field is concentrated on sharp edges or points displaced from each other in the direction of travel .of the wire which passes in close proximity to the edge portions of the members thus forming the poles of the magnetizing element.

For example, reference being had to Figs. 4 and 5, the magnetizing device is shownas consisting of a formed coil or annular bobbin 30 of wire including two sets of windings with respective terminal outlets 31 and 32, whereby the magnetomotive force 'ma be varied by either connecting said coil: in series or in'parallel with each other. Surrounding said bobbins are enclosing metal members in the nature of cups 33 and 34 which are arranged to fit the one within the other and the same are centrally perforated to permit the wire 20 to pass therethrough at 'an angle. These shells or cups may be secured to each other by means of insulating rivets '35 passing therethrough as well as an annular centrally disposed member of insulation 36 which serves also to support the coil 30. The one shell 33, also, has extending therefrom radially inwardly into its central opening a tooth or pointed portion 37 while, similarly, there extends radially inward from the other shell 34 into the central opening thereof a tooth or pointed element 38 which is diametrically disposed with respect to the tooth 37. These two teeth, of course, are laterally displaced from each other through the separating ring 36 and serve as pole pieces providing the flux for magnetizing, or rather reducing the magnetization, of the magnetically saturated wire 20 as the same is drawn therethrough. In reproducing, the action, of course, is the reverse.

In Fig. 6, the effective pole pieces are represented by the vertically-and horizontally displaced beveled edges 40 and 41, which are magnetized by a suitable winding 42 and connected by the yoke 43.

I claim:

1. In a telegraphone: the method of recording signals on a magnetizable body of high retentivity which consists in first magnetizing the body to a saturated state, and then passing the body while magnetically saturated through a magnetic field produced solely by a signalling current to suppress totally thereby the efiect on the magnetization of said bodv of one-half of the current wave.

2. In a telegraphone the method of record ing signals on a magnetizable body of high retentivity which consists in first magnetizing the body to a saturated state, and then passing the body while magnetically saturated through a magnetic field produced by a non-polarized signalling current to suppress totally thereby the effect on the magnetization of said body of one-half of the current wave. e v 3. In a telegraphone: a reproducing element magnetically saturated in part, all the remaining portions representing a half wave record.

4. An electromagnetic member foruse in telegraphones, comprising a magnetizing bobbin of wire, and an'enclosing metal casing centrally perforated to register with the bohbin opening and having, teeth projecting from its opposite sides radially into the opening.

5. An electromagnetic member for use in telegraphones, comprising a formed annular bobbin of wire withterminals for external connection and having a central opening to permit the passage therethrough of a magnetizable body, and an enclosing metallic casin centrally perforated to register with the b0 bin openin andhaving teeth projecting Erom its opposite sides radially into the openmg. v In testimony whereof I aflix my signature.

SYDNEY N. BABUOH. 

